1. Field of the Invention
The present invention relates generally to a gamma-butyrolactone production process and catalyst, and more particularly, to a process and catalyst for producing gamma-butyrolactone from maleic anhydride and/or succinic anhydride.
2. Description of the Prior Art
Gamma-butyrolactone is a stable compound which has a variety of uses, not the least of which is as an intermediate in the manufacture of various other compounds, e.g., vinylpyrrolidone.
The exothermic catalytic hydrogenation of maleic anhydride or succinic anhydride and/or other related compounds to produce gamma-butyrolactone is old and well established in the art. For example, U.S. Pat. No. 4,025,534 issued May 24, 1977 discloses a continuous process for producing gamma-butyrolactone by hydrogenating maleic anhydride in the presence of a catalyst comprised of cobalt oxide and palladium on a support of silica. The hydrogenation is carried out in two stages, the first at a temperature of 52.degree. C. to 100.degree. C. and the second at a temperature of 190.degree. C. to 220.degree. C.
U.S. Pat. No. 3,492,314 issued Jan. 27, 1970 is directed to a process for producing tetrahydrofuran and gamma-butyrolactone from maleic anhydride in a two-stage catalytic hydrogenation reaction or from succinic anhydride in a single stage catalytic hydrogenation reaction. The catalyst utilized in both processes is a nickel-rhenium catalyst supported on a carrier, such as silica gel, alumina, silica-alumina and the like.
While the prior art processes and catalysts have been utilized successfully in the production of gamma-butyrolactone, various reaction products in addition to gamma-butyrolactone are usually produced in significant quantities, often making the processes less than economically optimum. Examples of such additional reaction products are n-butynol, n-propanol, n-butyric acid, propionic acid, succinic acid and tetrahydrofuran. The processes and catalysts of the present invention, on the other hand, bring about high gamma-butyrolactone selectivity and high quantitative conversion of maleic anhydride and/or succinic anhydride to gamma-butyrolactone.
Thus, by the present invention an improved process for the production of gamma-butyrolactone from maleic anhydride and/or succinic anhydride starting materials are provided as well as a novel highly selective catalyst and a method of preparing such catalyst.